Left: This image shows merged laser-scan point clouds for San Diego International Airport's Terminal 1.

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Right: The laser-scan point cloud of a support column within the airport terminal shows true color.

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Douglas Kuypers is a one-man laser-scanning team. In an ongoing project to develop maintenance plan data for the San Diego International Airport, Kuypers, with the Denver office of Woolpert Inc., used 3-D laser scanning to capture this data in the airport's Terminal 1. Using laser scanning slashed field time from 1400 hours that would have been needed with conventional survey methods to just 235 hours.

Populating a geographical information system (GIS) is time-consuming, especially for something as complicated as an airport terminal. Woolpert's task was to deliver floor and ceiling plans that included all visible plumbing, mechanical, and electrical (PME) features for the airport's terminal buildings.

“Without laser scanning, it would have taken two-thirds of a year to measure the building,” said Kevin Stacy, P.S., project manager in Woolpert's surveying/global positioning system group. “And our scan ‘team' was just one person, whereas a traditional measurement team would have had two people.” That one-man “team” was Kuypers, a professional surveyor who's been involved with laser scanning since Woolpert first started investigating this technology.

Before Kuypers went into the field, there was careful planning. First, the San Diego Airport provided computer-aided drafting (CAD) drawings of the terminal that dated from 1970. Based on the drawings, a preliminary laser-scanning schematic was created.

“We used the drawings to determine how many scans we thought we would need, and laid that out on the plans,” said Stacy. Also based on the drawings, a conventional horizontal and vertical control network was designed that would be referenced during scanning. “My group is made up of surveyors, so we attacked it from a traditional survey viewpoint,” said Stacy. “We used targets and performed conventional survey traverse and leveling to keep our scans tight.”

To cut down the time needed onsite in San Diego for security clearance, Kuypers completed all the paperwork, background checks, and fingerprinting at his hometown Port Columbus (Ohio) International Airport. Once clearance was obtained, the information was transferred to San Diego. This reduced his onsite time for security badges, airport orientation, and pictures to just one day.

Adjusting Work Plans

Once he arrived onsite, Kuypers discovered that the work plan would have to be adjusted to accommodate field conditions that weren't reflected in the data provided for planning. “I found that scanning would have to be executed in two shifts,” he said. “We had previously thought I could work just during the day, but it turned out I would also have to work at night, to keep pedestrians out of the scan scene in order to cut down the time needed to process the scan data.” General public areas were scanned between 10 p.m. and 5 a.m., while airline offices, store areas, and restaurants were scanned between 10 a.m. and 5 p.m.

Because the survey work had to be done in an operating airport terminal, it was important to minimize the impact on the traveling public. Laser scanning is ideal for this. In many instances, scenes can be scanned even as pedestrians or vehicles continue passing through—the unneeded data is simply removed in post-processing, as was done with the airport's offices, stores, and restaurants.

But too great a volume of traffic through the scan scene can make this approach impractical—hence Kuypers' decision to carry out the majority of scanning at night, when traffic was light or nonexistent. (In fact all scanning was done at night, with two exceptions: areas where Kuypers needed an escort were scanned during the day shift when personnel were available, and lease areas—newsstands, coffee, food service, and the like—were scanned during their normal operating hours.) Traditional surveying also could have been done at night, but would have required a two-person crew, and would have required personnel to be onsite longer.

Kuypers adds that the floor plan provided by the airport was, not surprisingly, out of date; some wide-open spaces had been converted to smaller offices in the years since the plans were drawn. He also found that extra coordination would be needed to gain access to lease spaces and storage spaces.

But the unexpected conditions were not a problem. “Doug is a registered surveyor-he's our eyes and ears—so he can remain flexible,” said Stacy. “We felt it was best to have someone with crew-chief experience who's a registered surveyor, who would attack the job from that professional standpoint.”